Thursday November 20, 2025
Active NorCal —
An atmospheric river slammed into the Sierra this past weekend, sending the Merced River in Yosemite Valley surging more than 4 feet in 24 hours. The spike was recorded at the Happy Isles Bridge gauge, where river levels jumped from roughly 1.4 feet on Friday to 5.39 feet on Saturday, the highest November flow at that location since 1973.
Extreme weather chaser Colin McCarthy shared video of the roaring river, calling it “absolutely gushing.” He later noted that the Merced hit its third-highest November peak flow ever recorded, dating back to 1915, with a flow of 1,280 cubic feet per second.
The dramatic rise came as a powerful atmospheric river delivered heavy rain, strong winds, and widespread flood warnings across California. These storm systems, narrow columns of moisture that can carry more water than the Mississippi River, often hit the West Coast during winter, bringing both beneficial snowpack and dangerous flooding.
This storm leaned heavily toward the latter. Mudslides and flooding concerns triggered evacuations late last week, and the National Weather Service warned that “excessive runoff may result in flooding of rivers, creeks, streams, and low-lying areas.”
By Monday, the Merced River had already begun to drop, falling to about 3.2 feet at the Happy Isles gauge. Forecasters expect water levels to continue receding unless another round of rain arrives.
For now, Yosemite’s rivers are settling down, but this weekend offered a dramatic reminder of how quickly the Sierra can transform when an atmospheric river comes calling.